Species NameXiphophorus helleri
Common NameSwordtail
Care LevelEasy to Moderate
Lifespan3-5 years
Adult SizeUp to 6 inches
Minimum Tank Size20 gallons
Temperature72°F – 79°F (22°C – 26°C)
Water ConditionspH 7.0-8.3, 12-30 dGH

About the Swordtail – Species Summary

The Swordtail, scientifically known as Xiphophorus helleri, is a vibrant and elegant freshwater fish that is native to Central America. Their name derives from the elongated lower part of their caudal fin, which resembles a “sword”. This feature, especially pronounced in males, has made them a sought-after species in the aquarium hobby for decades. Available in a wide array of colors due to selective breeding, swordtails offer both novice and experienced aquarium keepers an attractive and lively addition to their community tanks.

Swordtail Lifespan

Swordtails generally have a lifespan ranging from 3 to 5 years in captivity. Factors influencing their lifespan include their genetic lineage, quality of care, and overall health. A consistent, well-balanced diet, pristine water conditions, and a stress-free environment significantly contribute to their longevity.


Swordtails are best known for their unique caudal fin extension, prominently seen in males, which gives the impression of a sword. Females lack this elongated “sword”, and while they are generally larger in body size, their tails remain rounded. Over the years, selective breeding has produced a variety of colors, from the natural olive green to brilliant reds, oranges, and even tuxedo patterns.

Average Size

When fully matured, swordtails can reach a length of up to 6 inches, with females typically being larger than males. However, the males boast a more pronounced “sword” tail extension, which can add an additional 2 inches to their length.

Swordtail Care

Tank Size

A minimum of 20 gallons is recommended for keeping swordtails. Given their active nature and potential size, larger tanks are often preferred, especially if planning to keep a group.

How To Set Up Their Tank

Swordtails thrive in tanks that mimic their natural habitats. A combination of fine gravel and sand works well as a substrate. Adding live plants, such as Java fern, hornwort, and Vallisneria, provides hiding spots and adds to their comfort. Open swimming areas are equally essential for these active swimmers.

Lighting Requirements

Moderate lighting complements the vivid colors of the swordtails and supports the growth of live plants in the tank. While they’re not particularly fussy about lighting, it’s essential to maintain a consistent day-night cycle.


The ideal pH for swordtails ranges between 7.0 to 8.3. While they can adapt to slight fluctuations, sudden changes can be detrimental and should be avoided.


Maintaining a water temperature between 72°F and 79°F (22°C to 26°C) is vital for swordtails. Investing in a reliable aquarium heater ensures consistency in the water temperature, crucial for their well-being.

Water Parameters

Swordtails prefer water hardness ranging from 12 to 30 dGH. Regular water testing ensures that parameters like ammonia, nitrate, and nitrite levels remain within the desired range.

Disease Potential

While swordtails are relatively hardy, they are not immune to common fish diseases like Ich, fin rot, or fungal infections. Quarantine procedures for new additions, regular water changes, and monitoring for signs of distress can help prevent most ailments.

Food & Diet

Being omnivorous, swordtails have a diverse diet. A mixture of high-quality flake food, supplemented with live or frozen treats like brine shrimp, bloodworms, and daphnia, ensures they receive all essential nutrients. Vegetables like zucchini and cucumber slices can also be occasionally offered.

Behavior and Temperament

Swordtails are peaceful and active swimmers. They are often seen darting around the tank and engaging with their environment. While they usually get along well with other fish, male swordtails can sometimes display territorial behaviors, especially during breeding times.

Tank Mates

Given their peaceful disposition, swordtails can coexist harmoniously with a variety of tank mates. Compatible companions include mollies, platies, tetras, and peaceful barbs. However, aggressive or fin-nipping species should be avoided.


Swordtails are livebearers, which means the females give birth to live fry instead of laying eggs. Breeding them is relatively straightforward in a well-maintained tank. A higher female to male ratio (3:1) is recommended to prevent undue stress on females. Once the fry is born, separating them from the adults is advisable, as they might be seen as food. The fry can be fed finely crushed flake food or specialized fry food until they grow larger.

Swordtail FAQs (Frequently Asked Questions)